Extensible column for a stool or the like



H223 EXTENSIBLE COLUMN FOR A STOOI.. OR THE LIKE Filed March 17, 1958Feb., 3, W5 s. D. SHEARMAN Err-Al.

2 Sheets-Sheet 1 Lin Feh, 95 s. D. SHEARMAN ETAL 2,872,223

EXTENSIBLE COLUMN FOR A sTooL 0R THE LIKE Filed March 17, 1958 UnitedStates Patent,

EXTENSIBLE COLUMN FOR A STOOL OR THE LIKE Spicer D. Shearman, Bryan,Ohio, and Bruce E. Herbolshemer, Garrett, Ind., assignors to GarrettTubular Products, Inc., Garrett, Ind.

Application March 17, 1958, Serial No. 722,066

16 Claims. (Cl. 287-5'8) The presentinvention relates to an extensiblecolumn for a stool or the like and more particularly to an extensiblesupport composed of a pair of relatively movable, telescoped membershaving locking means for selectively securing the members in any desiredextended length.

The extensible column of this invention is particularly useful in stoolsfor the purpose of varying the supported height of the seat with respectto the oor. This column, however, may be used in any structuralenvironment in which an adjustable extensible column locked againstcollapse is desired. Such a column has use in connection with towers,tables, furniture or as chair legs, and many other uses as will occur asobvious to a person skilled in the art.

The stool or similar supported device incorporating this invention isprovided with two relatively movable telescoping members, with one ofsaid members secured to the seat and the other of said members securedto the stool legs or base. A locking mechanism is interposed between thetwo members, which is operable to permit adjustment of the two memberswith respect to each other and to hold or lock the two members in suchadjusted position. This locking means is also provided withautomatically operable unlocking means whereby the two members may becollapsed completely one inside the other for reducing the length of thecolumn to a. minimum. A still further feature incorporated in thelocking mechanism is an arrangement for automatically returning thelocking mechanism to its normal operable condition, whereby theextension adjustment as previously explained may be obtained.

it is an object of this invention to provide an extensible column for astool or the like, which is infinitely adjustable in extended position.

It is still another object of this invention to provide an extensiblecolumn of infinitely adjustable length whereby the column may be securedin any extended position within its structural capabilities and lockedagainst collapse.

Other objects will become apparent as the description proceeds. v

To the accomplishment of the above and related objects, the inventionmay be embodied in the forms illustrated in the accompanying drawings,attention being called to the fact, however, that the drawings areillustrative only, and that specific change may be made in the specificconstruction illustrated and described, so long as the scope of theappended claims is not violated.

In the drawings:

Fig. l is a side elevation of a stool incorporating the presentinvention;

Fig. 2 is a longitudinal sectional illustration of the extensiblecolumn;

Fig. 3 is a perspective view of the locking sleeve par- 1tiallysectioned for clarity of illustration;

Fig. 4 is a view similar to Fig. 2 but with the telescoping membersextended to the maximum limit and the 2,872,223 'atented Feb. `3, r1959locking means moved to inoperative position prep-aratory to collapsingthe two telescoping members;

Fig. 5 is a sectional view similar to Fig. 4 but with the telescopingmembers completely collapsed and the locking mechanism returned to itsoperable position; and

Fig. 6 is a cross-section taken substantially on section line 6 6 ofFig. 5. y

Referring to the drawings, and more `particularly to Figs. l and 2, astool is shown having a seat 10 and legs 12, and an extensible support14 being connected therebetween. The extensible support 14 comprises twotelescoping members 16 and 18, which members are provided with lockingmechanism (to be described hereinafter) which permits raising the seat10 to any desired height within the limit of extension of the column 14.The supported height of the seat 10 is iixed merely by a slight downwardforce which serves to actuate thelocking mechanism preventing thecollapse of the telescoping members 16 and 18.

The extensible column 14 is shown more clearly in Fig. 2. The outermember 18 is tubular and preferably formed of cold rolled steel. In theopposite ends of the outer member 18 are xed two tubular sleeves orabutments Ztl and 22, respectively, which are involved in the operationof the locking mechanism to be explained in the following. The abutment22 is preferably cup-shaped as shown, but may be a sleeve ofsubstantially the same form as the sleeve 26. The inner wall of thetubular memberv 18 is preferably smooth, but the degree of smoothness isnot critical.

The inner member 16 is somewhat more complex in structure than the outermember 18 and is constructed to be freely, axially movable in the member18. The upper end of the inner member 16 is a post 26 suitably formedfor attachment to the stool seat 10. A hollow or tubular strut 28 istelescoped over the post 26 and is pinned or otherwise secured theretoby means of a roll pin 30. In the lower end of this strut 28 is receivedand secured the reduced diameter end 32 of the columnlockingsub-assembly. This reduced end 32 is secured to the strut end by meansof a roll pin or the like 34.

Axially extending from and immediately below the reduced end 32 is a camsupport 36 of cylindrical shape terminated in a truste-conical camsurface 3S which extends radially inwardly from the periphery of the camsupport 36. interposedV between this cam support 36 and the outer member18 is a releasing or tripping section or sleeve 40 of such size as to befreely movable with respect to both the outer member 18 and the camsupport 36 (or inner member 16).

An annular series of steel balls or rolling elements 42 surround the camsurface 38 and are of such diameter as to be wedged or locked betweenthis cam surface and the inner wall 24 of the outer member 18 when theinner column member 16 is forced in the collapsing direction.

Axially extending from the cam support 38 is a mounting stud 44 threadedat its lower extremity 46 for receiving a mo-unting nut 48. Received onthe stud 44 and secured thereto by nut 48 is a locking member 50 havingthree different diameter portions 52, 54 -and 56, respectively. Theportion 52 is the smallest and is disposed adjacent to'the cam surface38. The portion 54 is intermediate in size, and the portion 56 is thelargest. Each of these different diameter portions is joined to the nextportion by annular shoulders 58and 60, respectively. This locking member50 is secured to the inner member 16 and therefore may be considered asa part thereof.

Surrounding the locking member 50 is a locking sleeve 62 which isfreely, axially slidablerin the outer member 1.8.r The, inner wall` of,this, sleeve. 62 is divided into two..

different diameter lengths 64 and 66, which are joined by a chamferedsurface 68: The diameter 66 is large enough to. havev a clearance. fitwith the largest diameter portion 56 of the; sleeve-lockingmember. Thisbeing true, the sleeve 624 is free to move relative to the sleevelockingmember 541 when the sleeve portion 66 surrounds the portion 56.

The sleeve length 64, however, is smaller in diameter than the portion66, this diameter being slightly smaller than the outer diameter of thesleeve-locking member portion 56. Thus, when the sleeve portion 64 ismoved or telescoped over the enlarged' portion 56, an interference fitresults which frictionally locks the sleeve 62 onto the sleeve-lockingmember 50. Thus, the portion 6 4. 0 f the sleeve 62 is s aid to haveaninterference frictional tit with respect to thev enlarged portion 56of the sleeve-locking member, while the sleeve length 66 is. said tohavea clearance fit therewith.

Surrounding the intermediate diameter portion 54 of the sleeve-lockingmember is a compressed helical spring 71 which bears at one end againstthe shoulder 60 and at ther other end against a radially inwardlyprojecting ridge 79 onV the upper end of thev locking sleeve 62. Theupper surface 72 ofthis ridge is conically tapered and.' normallyengagedY with the balls 42. This tapered surface 72 normally urges theballs 42 radially inwardly toward the center of the inner member 16. Thespring 71 maintains the sleeve 62 in normal engagement with the. balls.42.

The balls 42 are straddled by the releasing and locking sectionswhich inthe illustrated embodiment comprise the two sleeves 40 and 62,respectively, both of theseIv sleeves having conically tapered ends 41and 72, respectively, which urge the balls radially inwardly.

The spring 71 need only bel strong enough to hold the sleeve surface 72into engagement with the balls 42 and should have a compressed heightwhich will allow the balls 42 to be moved into the` annular spacesurrounding the smallest portion 52 of the sleeve-locking mem.

ber 50.

While the sleeve 62 has been described as having a larger diameterportion 6 6, as will appear from the following, this portion may bedispensed` with in some instances. However,` it is preferred that thisportion 66 be. present inasmuch as it improves the operability of theentire assembly.

Since the smaller diameter length 64 of the sleeve 62 has aninterference. tit with the enlarged portion 56 of the sleeve-lockingmember 50, it is desirable to provide a series of axially extendingslots '74 substantiallyA coextensive with the length 64, which willpermit the sleeve to be expanded enough to it over the enlarged portion56 in gripping relation. While these slots are described, otherlfrictional gripping means mayl be used without departing from thespirit or scope of this invention.

With the extensible column as described used in the stool constructionof Fig. 1, the column will be upright with the inner member 16 uppermostand the outer member 18 lowermost. The stool is adjusted to a higher,fixed level .merely by pulling upwardly on the inner member 16 and thenreleasing the seat when the desired height has been reached. The member16 tends to fall downwardly under the force of gravity, but this isprevented by the wedge-locking effect of the balls 42 between the camsurface 3S and the inner wall 24 of the outer member 18. This raising orextending adjustment may be continued until the inner member 16 is fullyextended to the position where the upper end of the tripping sleeve 40meets the lower end of the abutment sleeve 20.

If it is desired to lower the seat 10,l the inner member 16 is fullyextended to the position shownin Fig. 4.`

in such extended position has. the -upper end of the tripping sleeve 40engagedT with the lower end of the abutment sleeve 20. Further upwardmovement of the inner member 16 results in relative movement between thesleeve 40 and the cam support 36, which relative movement yforces theballs 42 into the annular space between the portion S2 of thesleeve-locking member 50 and the inner wall of the outer member 18. Thediameter of this portion 52 has a size which will provide a radial spacebetween the. periphery thereof and the inner wall of the outer member,which is larger than the diameter of the balls or rolling elements 42.Thus,I with the balls so positioned, they areV unlocked, or, in otherwords, moved to inoperative position. The tapered faces on the two`sleeves 40 and 62 normally urge the balls 42 inwardly against theperiphery of the smallest portion 52.

ln addition to the balls 42 ybeing forced into retracted or inoperativeposition, the locking sleeve 62 is also forced downwardly with thesmaller diameter portion 64 frictionallyA sliding or telescoping overthe outer surface of the enlarged portion 56 of the sleeve-lockingmember. The interference tit between the sleeve and the member is suchthat the sleeve and member frictionally lock together, the force of thereturn spring 71 being insuiiici'ent to break this; frictional lock.

With the assembly so locked in retracted or inoperative position, theinner member 16 may be freely lowered or collapsed into the outer member1S. At the limit of the collapsing movement, the lower end 76 of thesleeve 62 engages the upper end of the abutment 22, and by exerting aslight downward or collapsing force on the inner member 16 the sleeve 62may be forced upwardly relative to the inner member until theinterference iit with the enlarged portion 56 is broken. This frees thesleeve 62 whereupon the spring 71 forces the balls 42 as well as thesleeve 4.9 upwardly until the balls enter the wedge-shaped, annularspacey between the cam surface 38 andithe outer member wall 24. Thecolumn 16 may once again be incrementally raised to any adjustedposition within the structural limits of the mechanism.

If the column is used inverted from the position just explained, itwould not be necessary to use the spring 71. However, it has been foundthat improved results areV obtained by using this spring regardless ofthe position in which the column is used.

Since spring force isV used in the mechanism, positive, lockingoperation is alwaysY assured, which prevents accidental release of thetelescoped members, which could `result in serious injury to a personsitting on the stool.

While the sleeve-locking member Sil has been shown asmounted on a stud44 extending from the inner member 16, an alternative embodiment of thisinvention has the. sleeve-locking member 50 integral with the innermember 16. This integral construction requires that the sleeve 62 beaxially split along its entire length so that it may be expanded enoughto be assembled over the sleeve-locking member.

Another form of the invention resides in eliminating the. second orintermediate diameter portion 54- in the sleeve-locking member, whichportion serves to center and retain the spring 71 in position.

A still further modification, which is regarded as falling within thescope of the invention, eliminates the tapers on the lower and upperends, respectively, of` the sleeves 40 and 62. While the removal ofthese tapers is not regarded as an equivalent of the. tapers,nevertheless, suchI alternative construction falls within the scope andspirit ofthis invention.

Other alternative constructions will occur toa person skilled in theartwithout departing, from the scope of this invention, such, as making thecross-sectional shape of thetelescoped members,l the related sleeves andother parts square or ovular. Al'so thev rolling elements 42 inay becylindrical instead of spherical.

Whatisclaimedie.. l

1. For use in combination'with a stool'or the like, two relativelymovable telescoped members, the outer member being tubular, afrusta-conical cam surface on the inner member between the ends thereof,a reduced diameter portion on said inner member joining said camsurface, said cam surface extending radially inwardly from said reduceddiameter portion, a plurality of balls lockingly engageable with saidcam surface and the inner wall of said outer member, a tripping sleevesurrounding said reduced diameter portion and engageable at one end withsaid balls, said sleeve being movable relative to both of said members,a mounting stud on said inner member coaxially extending from said camsurface, a sleeve-locking member secured on said stud and having threestepped diameter portions which are joined in annular shoulders andarranged with the smallest and largest diameter portions on oppositesides of the intermediate diameter portion, the smallest portiondisposed adjacent said cam surface and having a diameter smaller thanthe diameter of said cam surface, said balls having a diameter smallerthan the radial space between said outer member and said smallestdiameter portion, a lockingA sleeve surrounding said sleeve-lockingmember freely axially slidable in said outer member, an annular ridge atone end of said sleeve which projects radially inwardly toward saidsmallest diameter portion of said sleevelocking member, the innerdiameter of said ridge clearing atleast said smallest diameter portion,a depressed conically tapered surface on the outer end of said ridgeengageable with said balls on the side opposite said tripping sleeve forurging them radially inwardly toward said inner member, the inner wallof said locking sleeve being divided into two dilerent diameter lengthsjoined by a chamfered surface, the larger diameter length extending fromthe end of said sleeve opposite said ridge and having a clearance litwith the largest diameter portion of said sleeve-locking member, thesmaller diameter length being intermediate the ends of said lockingsleeve and having a frictional interference iit with said largestdiameter portion but a clearance t with the intermediate diameterportion, said locking sleeve having an axially extending split along itssmaller diameter length, a compressed helical spring surrounding saidintermediate diameter portion and bearing at one end against the annularshoulder formed with the largest diameter portion and at its other endagainst said ridge for urging said locking sleeve into engagement withsaid balls and said balls into locking engagement with said cam surfaceand said outer member, said larger diameter length surrounding saidlargest diameter portion when said balls are in lockingposition and saidsmaller diameter length surrounding and frictionally engaging saidlargest diameter portion when said balls are in unlocked position, andtwo annular abutment elements secured to the opposite end portionsrespectively of said outer member for selective engagement with saidtripping and locking sleeves respectively, said inner member beingmovable inside said abutment elements.

2. For use in combination with a stool or the like, two relativelymovable telescoped members, the outer member being tubular, afrusto-conical cam surface on the inner member between the ends thereof,a reduced diameter portion on said inner member joining said camsurface, said cam surface extending radially inwardly from said reduceddiameter portion, a plurality of balls lockingly engageable with saidcam surface and the inner wall of said outer member, a tripping sleevesurrounding said reduced diameter portion and engageable at one end withsaid balls, said sleeve being movable relative to both of said members,a sleeve-locking member secured to and axially extending from said camsurface, said sleeve-locking member having three stepped diameterportions which are joined in annular shoulders and arranged with thesmallest and largest diameter portions on opposite sides of theintermediate diameter portion, "the smallest portion disposed adjacentsaid cam surface and having a diameter smaller than the diameter of saidcam surface, said balls having a diameter smaller than the radial spacebetween said outer member and said smallest diameter portion, a lockingsleeve surrounding said sleeve-locking member freely axially slidable insaid outer member, an annular ridge at one end of said sleeve whichprojects radially inwardly toward said smallest diameter portion of saidsleeve-locking member, the inner diameter of said ridge clearing atleast said smallest diameter portion, a depressed conically taperedsurface on the outer end of said ridge engageable with said balls on theside opposite said tripping sleeve for urging them radially inwardlytoward said inner member, the inner wall of said locking sleeve beingdivided into two different diameter lengths joined by a chamferedsurface, the larger diameter length extending from the end of saidsleeve opposite said ridge and having a clearance t with the largestdiameter portion of said sleeve-locking member, the smaller diameterlength being intermediate the ends of said locking sleeve and having africtional interference t with said largest diameter portion but aclearance fit with the intermediate diameter portion, said lockingsleeve being axially split along its smaller diameter length, acompressed helical spring surrounding said intermediate diameter portionand bearing at one end against the annular shoulder formed with thelargest diameter portion and at its other end against said ridge forurging said locking sleeve into engagement with said balls and saidballs into locking engagement with said cam surface and said outermember, said larger diameter length surrounding said largest diameterportion when said balls are in locking position and said smallerdiameter length surrounding and frictionally engaging said largestdiameter portion when said balls are in unlocked position, and twoannular abutment elements secured to the opposite end portionsrespectively of said outer member for selective engagement with saidtripping and locking sleeves respectively, said inner member beingmovable inside said abutment element.

3. For use in combination with a stool or the like, two relativelymovable telescoped members, the outer member being tubular, afrusto-conical cam surface on the inner member between the ends thereof,and extending radially inwardly from the periphery of said inner member,va plurality of balls lockingly engageable with said cam surface and theinner Wall of said outer member, a tripping `sleeve surrounding saidinner member and engageable at one end with said balls, said sleevebeing movable relative to both of said members, a sleeve-locking memberhaving three stepped diameter portions which are joined in annularshoulders and arranged with the smallest and largest diameter portionson opposite lsides of the intermediate diameter portion, the smallestportion secured adjacent said cam surface and having a diameter smallerthan the diameter of said cam surface, said balls having a diametersmaller than the radial space lbetween said outer member and saidsmallest diameter portion, a locking sleeve surrounding saidsleeve-locking member freely axially slidable in said outer member, anannular ridge at one end of said sleeve which projects radially inwardlytoward said smallest diameter portion of said sleeve-locking member, theinner -diameter of said ridge clearing at least said smallest diameterportion, a depressed conically tapered surface on the outer end of saidridge engageable with said balls on the side opposite said trippingsleeve for urging them radially inwardly toward said inner member, theinner wall of said locking sleeve being divided into two differentdiameter lengths joined by :a chamfered surface, the larger diameterlength extending from the end of said sleeve opposite said ridge andhaving'a clearance t with the largest diameter portion of saidsleeve-locking member, the smaller diameter length being intermediatethe ends of said locking sleeve.

assenze audi having, a; irietional interference t. with, said. largestdiameter portijorrbut. aclearanee. lit withthe interrmerli'ateA diameterportion,l a` coirlpressed helical spring surround.- ing said;intermediate, diameter portion and bearing at one endfagainst theannular shoulder formed with the largestA diameter portion and at itsother end against said ridge for urging said locking sleeve intoengagement with said. ballsl and said balls into locking` engagementwith said camV surface 'and said outer member, said lar er diameterlength surrounding said-.largest diameter portion whensaid ballsare inlockingpositionand said smaller diameter length surrounding andfrictionally engaging said largest diameter portionwhen said balls arein unlocked positiom and two annular abutment elements securedto the`opposite end portions respectively of 'said outer member for,selectiveengagement with said tripping and locking sleeves respectively,said inner member being movable inside said abutment elements.

4'. For use incombination with a stool or the like, two relativelymovable telescoped members, the outer member being tubular, afrusto-conical cam` surface on the inner member between the ends thereofandV extending radially inwardly from the periphery of said innermember, a plurality of balls lockingly engageable with said cam surfaceand the inner wall of' said outer member, a tripping sleeve surroundingsaid inner member and engageable atone endwith said balls, said sleevebeing movable relative to,V both said members, a sleeve-locking memberhaving three steppeddiameter portions which are joined in annularshoulders and arranged with the smallest and largest diameter portionsAon opposite -sides of the intermediate diameter portion, said'sleeve-locking member being secured to said inner member with thesmallest portionadiacent tosaid. cam surface and having a diametersmaller than the diameterof'said cam surface, said ballsV having aVdiameter smaller than the radial space.

between said outer member and said smallest diameter portion, a lockingsleeve surrounding said sleeve-locking member freely axially slidable insaid outer member, an annular ridge at, one endl of vsaid sleeve whichprojects radiallyinwardly toward` said smallest diameter portion of saidsleeve-locking member, the inner diameter of said ridge clearing atleast said smallest diameter portion, a depressed conically taperedsurface onthe outer end of said ridge engageable with said balls on theside opposite said tripping sleeve for urging them radially inwardlytoward said inner member, the inner Wall of said locking sleeve beingdivided into two different diameter lengths joined by a chamferedsurface, the larger diameter length extending from the cnd of saidsleeve opposite said ridge and having a clearance tit with the. largestdiameter portion of said sleeve-locking member, the smaller diameterlength being intermediate the ends of said locking sleeve and having africtional interference fit with said largest diameter portion but aclearance fit with the intermediate diameter portion, means foryieldably urging said locking sleeve into engagement with said balls andsaid balls into locking engagement with said cam surface and said outermember, said larger diameter length surrounding said largest diameterportion when said balls are in lock` ing position and said smallerdiameter length surrounding and frictionally engaging said largestdiameter portion when said 'balls are in unlocked position, and twoabutment elements secured near the opposite ends of said outer memberfor selective engagement with said tripping and locking sleevesrespectively, said inner member being movable relative to saidabutmentelements.

5. For use in combination with a stool or the like, two relativelymovable telescoped members, the outer member'being tubular, atruste-conical cam surface on the inner member between the ends thereofand extending radially inwardly from the periphery of said inner member, va plurality' of balls loc'kingly engageable withY said.

s gageable; atr one: end with said balls,T said sleeve.- being movablerelative to both said.. members, asleeve-locking member having three.stepped diameter portions. whichv are j oiued in. annular shoulders andarrangedk with. the

smallest and. largest diameter. portions on opposite sides4 of the.intermediate, diameter portion, saidk sleeve-locking memberbeingqsecured to said inner member with, the

smallest portion disposed adjacent to said. cam surface' and having avdiameter. smaller than the diameter of Said.

cam surface, said' balls having a diameter smaller than the radialspa-:e between said outer member and said smallest diameter portion, alocking sleeve surrounding said lsleeve-locking member freely axiallyslidable in said outer member, an annular ridge atone end ofsaid'sleeve.

which projects radially inwardly toward said smallest diameter portion.of. said sleeve-locking member, the inner. diameter of said ridgeclearing at least said smallest diam.- eter portion, a depressedconically tapered surface on the outer end of said ridge engageablewith. said balls on the side oppositeV said. tripping sleeve for urgingthem radially inwardly toward said inner member, the inner wall of. saidlocking sleeve being divided into two different diameter lengths joinedby a charnfered surface, the larger diameter length extending from theend of said sleeve opposite said ridge and having a clearance t with thelargest diameter portion of said sleeve-locking member., the smallerdiameter length being intermediate the ends of said locking sleeve andhaving a frictional interference ht with said largest diameter' porti-onbut a clearance ritv with the, intermediate diameter portion, means forurging said locking sleeve into engagement with said balls and" saidballs into locking engagement with said cam surface and said outermember, said larger diameter length surrounding saidV largest diameterportion when said balls are in locking position and said smallerdiameter. length surrounding and frictionally engaging said largestrdiameter portion when said balls are in' unlocked position, and twoabutment elements nearthe opposite end portions respectively of saidouter member. for selective engagement with said tripping and lockingsleeves respectively, said inner member being movable relative to saidabutment elements.

6. For use in combination with a stool or the like, two relativelymovable telescoped members, the outer member being tubular, atruste-conical cam surface on the inner member between the ends thereofand extending radially inwardly from the periphery of said inner member,a

plurality of rolling elements lockingly engageable with saidv camsurface and the inner wall of said outer member,- a tripping sleevesurrounding said inner member andengageable at one end with said rollingelements, said sleeve being movable relative to both said members,

a sleevedocking member having at least two stepped. diameter portions,said sleeve-locking member extending;

lengths, the larger diameter length extending from. thel end of saidlocking` sleeve opposite said one end and hav-V ingaclearance lit withthe-larger diameter portion of said sleeve-locking member, the smallerdiameter length.

of said locking sleeve having a frictional interferencet with saidlargerdiameter portion but a clearance fit with the smaller diameterportion, means for urging said loci;- ingsleeve into engagement withsaid rolling elements and saidrollingelements' into lockingengagement..withsaid cam surface 'and VsaidV outer .memben saidzlarger`,diameter length surrounding said larger diameter portion when saidrolling elements are in locking position and said smaller diameterlength surrounding and frictionally engaging said larger diameterportion when said rolling elements are in unlocked position, and twoabutment elements near the opposite end portions respectively of saidouter member for selective engagement with said tripping and lockingsleeves respectively, said inner member being movable relative to saidabutment elements.

7. For use in combination with a stool or the like, two relativelymovable telescoped members, a tapered cam surface on the inner memberbetween the ends thereof and extending radially inwardly from theperiphery of said inner member, at least one rolling element lockinglyengageable with said cam surface and the inner Wall of said outermember, a tripping sleeve surrounding said inner member and engageableat one end with said rolling element, said sleeve being movable relativeto both said members, a sleeve-locking member having at least twostepped diameter portions, said sleeve-locking member extending axiallyfrom and being secured to said inner member with the smaller diameterportion disposed adjacent to said cam surface, said rolling elementbeing smaller than the radial spacing between said outer member and saidsmaller diameter portion, a locking sleeve surrounding saidsleeve-locking member freely axially slidable in said outer member, aprojection at one end of said sleeve which extends radially inwardlytoward said smaller diameterportion of said sleeve-locking member, theinner portion of said projection clearing said smallest diameterportion, said projection being engageable with said rolling elem-ent onthe side opposite said tripping sleeve for urging said rolling elementradially inwardly toward said inner member, the inner wall of saidlocking sleeve being divided into two different diameter lengths, thelarger diameter length extending from the end of said sleeve oppositesaid projection and having a clearance t with the largestdiameterportion of said sleeve-locking.

member, the smaller diameter length being intermediate the ends of saidlocking sleeve and having a frictional interference t with said largerdiameter portion but a clearance tit with the smaller diameter portion,means for urging said locking sleeve into engagement with said rollingelement and said rolling element into locking engagement with said camsurface and said outer member, said larger diameter length surroundingsaid largest diameter portion when said rolling element is in lockingposition and said smaller diameter length surrounding and frictionallyengaging said largest diameter portion when said rolling element is inunlocked position, and

two abutment elements near the opposite end portions respectively ofsaid outer member for selective engagement with said tripping andlocking sleeves respectively, said inner member being movable relativeto said abutment elements.

8. For use in combination with a stool or the like, two relativelymovable telescoped members, a frusta-conical cam surface on the inn-ermember between the ends thereof and extending radially inwardly from theperiphery of said inner member, a plurality of rolling elementslockingly engageable with said cam surface and the inner wall of saidouter member, a tripping sleeve surrounding said inner member andengageable at one end with said rolling elements, said sleeve beingmovable relative to both said members, a sleeve-locking member extendingaxially from and secured to said inner member adjacent to said camsurface, said sleeve-locking member' having a small diameter portionadjacent said cam surface and a larger diameter portion remote from saidcam surface, s aid rolling elements having a diameter smaller than theradial space between said outer member and said smaller diameterportion, a locking sleeve surrounding said sleevelocking member freelyaxially slidable in said outer member, one end of said locking sleevebeing engageable with rolling elements on the side opposite saidtripping sleeve, the inner wall of said locking sleeve being dividedinto two axially spaced different diameter lengths, thelag'e diameterlength of said sleeve having a clearance fit with the larger diameterportion of said sleeve-locking member, the smaller diameter lengthhaving a frictional interfer ence fit with said larger diameter portion,said larger diameter length surrounding said larger diameter portionwhen said rolling elements are in locking position and said smallerdiameter length surrounding and frictionally engaging said largerdiameter portion when said rolling elements are in unlocked position,means for urging said locking sleeve into engagement with said rollingelements and said rolling elements into locking engagement with said camsurface and said outer member, and two abutment elements near theopposite end portions respectively of said outer member for selectiveengagement with said tripping and locking sleeves respectively, saidinner mem-y ber being movable relative to said abutment elements.

9. For use in combination with a stool or the like, two relativelymovable telescoped members, a tapered cam surface on the inner memberbetween the ends thereof and extending radially inwardly from theperiphery of said inner member, a plurality of rolling elementslockingly engageable with said cam surface and the inner wall of saidouter member, a tripping sleeve surrounding said inner member andengageable at one endwith said rolling elements, said sleeve Ibeingmovable relative to both said members, an annular recess in said innermenn-l ber adjacent to the smaller diameter portion of said cam surface,an enlarged portion on said inner member adjacent to said recess on theside opposite said cam sur face, said rolling elements having a diametersmaller than the radial space between said recess and said outer member,a locking sleeve surrounding said enlarged portion freely axiallyslidable in said outer member, one end of said locking sleeve beingengageable with said rolling elements on the side opposite said trippingsleeve, the inner wall of said locking sleeve being divided into twoaxially spaced diiferent diameter lengths, the larger diameter lengthhaving a clearance t with said enlarged portion, the smaller diameterlength having a frictional interference t with said enlarged portion,said larger diameter length surrounding said enlarged portion when saidrolling elements are in locking position and said smaller diameterlength surrounding and frictionally engaging said enlarged portion whensaid rolling elements are in unlocked position, means for urging saidlocking sleeve into engagement with said rolling elements and saidrolling elements into locking engagement with said cam surface and saidouter member, and two abutment elements near the opposite end portionsrespectively of said outer member for selective engagement with saidtripping and locking sleeves respectively, said inner member beingmovable relative to said abutment elements.

l0. For use in combination with a stool or the like, two relativelymovable telescoped members, a tapered ca m surface on the inner memberbetween the ends thereof and extending radially inwardly from theperiphery of said inner member, a plurality of rolling elementslockingly engageable with said cam surface and the inner wall of saidouter member, a tripping sleeve surrounding said inner member andengageable at one end with said rolling elements, said sleeve beingmovable relative to both said members, an annular recess in said innermember adjacent to the smaller diameter portion of said cam surface, anenlarged portion on said inner member adjacent to said recess on theside opposite said cam surface, said rolling elements having a diametersmaller than the radial space between said recess and said outer member,a locking sleeve surrounding said enlarged' portion freely axiallyslidable in said outer member, one end of said locking sleeve beingengageable with said rolling elements on the side opposite said trippingsleeve, theinner wall of said locking sleeve being divided, into twoaxially spaced different diameter lengths, the larger diameter lengthhaving a clearance lit with said enlarged l portion, that smallervdiameter length having a frictional interference tit with` said enlargedportion, said larger diameter length surrounding said enlarged portionwhen said rolling elements are in locking position and said smallerdiameter length surrounding and frictionally engagingsaid enlargedportion when said rolling elements are in unlocked position, and twoabutment elements near the opposite end portions respectively of saidouter member for selective engagement with said tripping and lockingsleeves respectively,. said inner member being movable relative to saidabutment elements.

ll. For use in combination with a stool or the like, two relativelymovable telescoped members, the outer member being tubular, afrusto-conical cam surface on the inner member between the ends thereofand extending radially inwardly from the periphery of said inner member,a plurality of rolling elements lockingly engageable with said camsurface and the inner wall of said outer member, a tripping sleevesurrounding said inner member and engageable at one end with saidrolling elements, said sleeve being movable relative to both saidmembers, a sleeve-locking member having at least two stepped diameterportions, said sleeve-locking member extending axially from and beingsecured to said inner member with the smaller diameter portion disposedadjacent to said cam surface, said rolling elements having a diametersmaller than the radial spacing between said outer member and saidsmaller diameter portion, a locking sleeve surrounding saidsleeve-locking member freely axially slidable in said outer member, oneend of said locking sleeve being engageable with said rolling elementson the side opposite said tripping sleeve, the inner wall of saidlocking sleeve being divided into two different diameter lengths, thelarger diameter length extending from the end of said locking sleeveopposite said one end and having a clearance tit with the largerdiameter portion of said sleeve-locking member, the smaller diameterlength of said locking sleeve having a frictional interference tit withsaid larger diameter portion but a clearance t with trie smallerdiameter portion, said larger diameter length surrounding said largerdiameter portion when said rolling elements are in locking position andsaid smaller diameter length surrounding and frictionally engaging saidlarger diameter portion when said rolling elements are in unlockedposition, and two abutment elements near the opposite end portionsrespectively of said outer member for selective engagement with saidtripping and locking sleeves respectively, said inner member beingmovable relative to said abutment elements.

l2. For use in combination with a stool or the likev` two relativelymovable telescoped members, a tapered cam surface on the inner memberextending inwardly from the periphery thereof, at least one rollingelement lockingly engageable with said cam surface and the inner wall ofthe outer telescoped member, a tripping element interposed between andrelatively movable with respect to said telescoped members, saidtripping ele ment being engageable with said rolling element, a recessedportion in said inner member adjacent to the radially inner portion ofsaid cam surface, an enlarged portion on said inner member adjacent tosaid recessed portion on the side opposite said cam surface, a lockingsleeve surrounding said recessed and enlarged portions and beingengageable with said rolling element on the side opposite from saidtripping element, said sleeve be ing movable inside said outerfmember,the inner wall of said sleeve being axially divided into two differentdiameter lengths, the larger diameter length having a clear ance titwith said enlarged portion, the smaller diameter portion having africtional tit with said enlarged portion, means yieldably urgingsaid-sleeve into engagement with saidrrolling'elemennand two abutmentson'said. outer member engageable respectively by saidtripping element f2apart in straddling relation to the tripping element in as'sen'rb'lyVwith the locking sleeve.

13. For use in combination ith a stool or the like, two relativelymovable' telescoped members, a tapered cam surface onv the inner memberextending inwardly from the periphery thereof, at least one rollingelement lockingly engageable with said cam'stirface and the inner wallof the outer telescoped member, a tripping element interposed betweenand relatively movable with respect to said t'elescopedY members, saidtripping element being engageable with said rolling element, `a recessedportion in said inner member adjacent to the radially inner portion ofsaid cam surface, an enlarged portion on saidl inner member adjacent tosaid recessed portion on the side opposite said cam surface, a lockingsleeve surrounding said recessed and enlarged portions and beingengageable with said rolling element on the side opposite from saidtripping element, said sleeve being movable inside said outer member,the inner wall of said sleeve being axially divided into two diterentdiameter lengths, the larger diameter length having a clearance t withsaid enlarged portion, the smaller diameter portion having a frictionaltit with said enlarged portion, and two abutments yon said outer memberengageable respectively by said tripping element and said lockingsleeve, said abutments being spaced apart in straddling relation to thetripping element in assembly with the locking sleeve.

14. For use in combination with a stool or the like,

two relatively movable telescoped members, a tapered cam surface on theinner member extending inwardly from the periphery thereof, at least onerolling element lockingly engageable with said earn surface and theinner wall of the outer telescoped member, a tripping element linterposed between and relatively movable with respect to saidtelescoped members, said tripping element being engageable with saidrolling element, a recessed portion in said inner member adjacent to theradially inner portion of said cam surface, an enlarged portion on saidinner member adjacent to `said recessed portion on the side oppositesaid cam surface, a locking sleeve surrounding said recessed andenlarged portions and being engageable with said rolling element on theside opposite from said tripping element, said sleeve being movableinside said outer member, the inner wall of said sleeve being axiallydivided into two different diameter lengths, the larger diameterlengthhaving a clearance tit with said enlarged portion, the smaller diameter'portion having a frictional iit with said enlarged portion, and meanstor selectively' alternatively forcing said tripping element and saidlocking sleeve into engagement with said rolling element.

ISL For use in combination with a stool or the like, two relativelymovabletelescoped members, a tapered cam surface on the'inner memberextending inwardly from the periphery thereof, at least one rollingelement lockingly engageable with said cam surface and the inner wallofthe outer telescoped member, releasing and locking means comprisingreleasing and locking sections relatively movable with respect to saidtelescoped members, said releasing'section being engageable with saidrolling element, alocking member on said inner member on the side of'said cam surface opposite said releasing section, said locking sectioninterposed between said inner and outer members and engageable with saidrolling element on the side opposite said releasing section, and meansfor locking said locking member and said locking section together atairst relative position therebetween which retraetssidlocking'sectionfrom said rolling element, andmeans' for selectively unlocking saidlocking section from said locking member at a second relative positionthere between which disposes said locking section into engagement withsaid rolling element.

16. For use in combination with a stool or the like, two'rel'ativelymovablete'lesc'oped members, a tapered cm-srirfacefon-,the inner-'memberextendingl inwardly' from tho-periphery thereof, -at leastl one-rollingieler'nerit' diierent diameter lengths, the larger diameterlength having a clearance t with said friction element and the smallerdiameter length having a frictional t with said friction element, andmeans selectively moving said locking sleeve into and out of frictionalengagement with said friction element for locking and unlocking saidrolling element respectively.

No references cited.

